Two-stroke internal-combustion engine



A. M. IMHOFF. I TWO-STROKE INTERNAL COMBUSTION ENGINE.

APPLICATION FILED MAR. 26, I918.

Patented Apr. 12, 1921.

, llll Qumran sr-Arss" PATENT orrlce.

- iinqusrr ex IMEOEEOF IBERNE, swrrznnnam), ASSIGNOR r mnorr oron 00.,

4.0., or :NTERLAKEN, SWITZERLAND, A CORPORATION or SWITZERLAND.

To-all whom it may concern i ."Be it lmown that I, Anens'r siding lat Berne, Switzerland, have invented- 'rwo-s'rnoxn' INTERNAL-COMBUSTION Enema I MAX ma a" citizen or the Swiss Confederation and rea certain new and useful Improved Two- Stroke Internal-Combustion Engine," whichthe following is a speclfic'ation.

- Thepresent-invention relates to improvements in two cycle explosion engines of the type Kim-which the fuel-is subjected to pre- -l1minary compression in the crank casing,

. 'andvin, which engines the control of the inletand exhaust is efi'ected by a valveless iston having a centrally raised head. he

pistonis provided throughout its extent with piston rings, and in the cylinder wall are two superimposed series of ports, one series of rts serving for the admission of the fuei dharge and the other for the exhaust.

It has been demonstrated by experience that to secure maximum operating efiiciency of the motor, it is important that the enterin g'fuel beidirected without shock, into a central axial column flowing toward the cylinder head. Zone of the means suggested for iaccomplishing this purpose consisted in imparting an inwardly extending curvature to the centrally raised piston'head. Despite the adoption of this expedient the streams of gases impact against each other over the middle of the piston head to such an extent as to cause disturbing eddies.

' The principal object of vthe present inventi gn is to obviate the-disturbing condition a ove object provide the piston head with radial ribs which register with the intactfipor- .tions of the cylin er between the admission ports, when the piston is in a position to admit fuel to the cylinder. Byv means of these ribs the fuel issuing through the inlet ports is directed inwardly in the formof streams,' without the streams at first coming into contact. ,with" each other. 5- Gradually these: streams areso deflected that when they issue I than the radial ribsf'ofi the piston head, so

thatthe'entering'streams of fuel do not imoration. It is obvious that in this manner Specification of Letters Patent.

liointe'd out, and to accomplish this Patented A t. 1 21 921 Application filed March 26,1918. Serial No. 224,706.

pinge gainst these ribs but are free 65 An. embodiment of the invention is il1us-,

between the same.

tratively exemplified in the accompanying drawing. in which- I Figure 1 1s a vertical sectional view I through my improved engine;- 1 Figs. 2 and 3, are transversesectional views on the lines II-II and III-III, respectlvely, of Fig. 1. Mounted on the two part completely-closed crank casing 1 is the cylinder 5. In a cylindrical extension 2, of the crank'casing is a slide valve 3 which is positively driven by I suitable means. (not shown) from the cran shaft 10, and communicates .with a carbureter (not shown) and also through the duct 11 with the interior ofthe crank casing 1, which serves for the preliminary compression of the charge. The crank shaft is driven from the p1ston 4, reciprocable in the cylinder 5, b means of the pitman 12. The entire perip ery-of the piston is provided the center and provided with an inwardly directed curvature'or depression. Extending entirely about the inner periphery of the wall of the cylinder 5 are two series of ports 6 and 7. The ports 6 communicate :with piston rings, and its head is raised at with the crank casing through an annular passa e 8 formed in the lower part of the cylin er. Projecting from the curvature thereofare ribs 13 extending radially 'of the axis of the cylinder. When tion these ribs register with the intact portions between the admission ports fih These the piston head beyond the piston is in its lower dead-point posiintact portions gradually decreasein fwidth outwardly. As a result of this construction the eddies rushing into the cylinder during T the inflow of the charge are so guided that they pass between two adjacent ribs of. the

piston without impinging'again'st'th' piston, thereby preventing isturbance in the flow of the chargewliich might result if the as contacted frictionally with the ribs. he

fresh gases are completely deflected into anaxial direction between the ribs so'that;

when the individual streams of gas issue from the spaces between the ribs they do not meet in a manner'to cause disturbance-of on 10 eddying can be absolutely avoided. The fresh gases then move upwardly in the middle of the cylinder against the head thereof, whence they are caused to move down wardly along the cylinder wall.

The exhaust gases are conducted through the fresh gases tothe ports 7 and are exhausted out of the cylinder therethrough. The intact portions between the exhaust ports become narrower toward the interior of the cylinder (the reverse of the intact portions between the inlet ports (5) in order that the entrance of the exhaust gases into the ports 7 may occur without eddy formation. The exhaust ports 7 widen outwardly in the vertical direction and are arranged in a curve such that the direction of motion of the exhaust gases toward the ports 7, partly determined by the piston head, is preserved in the ports 7. Between the se-- 7 ries of admission ports 6 and exhaust ports 7 the cylinder wall presents a small intact arela extending entirely'around the cylinder wa 1.

The spaces between the piston rings on the outer face of the piston are so small that there is always at least one piston ring on the intact area between the ports 6 and 7, except during the period of inflow of the fresh gas.

What I claim is A two cycle engine, comprising a crank casing wherein fuel is compressed, a cylinder carried-by said casing and having a series of fuel inlet ports each of which decreases in width toward the interior of the cylinder whereby intact parts of relatively substantial area are present between adjacent inlet ports, and a piston reciprocable in said cylinder, said pistonhaving its head,

depressed and a plurality of spaced radial ribs extending from the piston head, whereby when said piston is in position to admit fuel to the oyllnder the ribs will aline with the intact parts between the inlet ports and the spaces between the ribs will aline with 7 said inlet ports so that the fuel will enter the said cylinder in substantially parallel streams without the formation of eddies.

In testimony whereof, I affix my signature in the presence of two witnesses.

AUGUST MAX IMHOF F.

Witnesses FRIEDRICH Nansen, Fnmnmon MONING. 

